Add undo/redo support to MindMapEditor

[Pragzh]

What changed

• Added undo and redo support to the MindMapEditor.
• Added Undo and Redo buttons in the toolbar.
• Added keyboard shortcuts for Ctrl+Z and Ctrl+Y.
• Saved editor history before node drag, delete, edit, import, template, and arrange actions.

Why

Users previously had no way to recover from accidental edits while creating or modifying mind maps.

Testing

• Added a node and verified Undo removes it.
• Used Redo to restore the node.
• Moved a node and verified Undo restores the previous position.
• Deleted a node and verified Undo restores it.
• Tested Ctrl+Z and Ctrl+Y shortcuts.
• Ran npm run build successfully.

Fixes #109

[vercel]

@Pragzh is attempting to deploy a commit to the Lovely Mahour's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Pragzh]

Hi @maintainer, my PR checks are failing because Vercel deployment needs team authorization. Could you please authorize the Vercel check when possible? Thank you!